1. Field of the Invention
The present invention relates to a video-signal processing apparatus and method, recording medium and program, and more particularly to a video-signal processing apparatus and method, recording medium and program adapted for display with quality by suppressing against image deterioration in the case a reception signal contains a data broadcast signal.
2. Description of the Related Art
With reference to FIG. 1, a conventional digital broadcast system will be explained.
In the case of using a high-vision television receiver or double-speed-conversion television receiver in combination with a digital tuner, when the digital tuner outputs a 480I broadcast signal to the television receiver, the television receiver format-converts the 480I broadcast signal into a high-vision signal (e.g. 720p, 1080I) or double-speed signal (e.g. 480p, 960I) with an incorporated double-speed conversion function, thereby outputting and displaying an image with quality.
In the meanwhile, in the digital broadcast system utilizing satellites or the like, there exist a broadcast having only a video signal (moving image) to be displayed over the entire screen (ordinary broadcast) and a data broadcast having character or figure data signal to be displayed in combination with a video signal.
In a data broadcast, the determination whether to broadcast a video signal in order for display in combination with a data signal or not is relied upon the broadcaster. At present, it is a practice for the broadcaster to broadcast many data-broadcast programs so that they are displayed by a video signal mixed in a character or figure data signal, as shown in FIG. 1A. In this case, the video signal is displayed in a reduced size (in the case of FIG. 1, the video-signal screen size (horizontal and vertical sizes) is a half of that of upon the ordinary broadcast).
In the meanwhile, the data-broadcast signal is broadcasted usually as a 480I signal. As a result, the video signal of data broadcast is processed for being reduced in its screen size in a digital tuner, followed by being format-converted from 480I into 480p or 960I in a television receiver. Namely, the video signal, thinned out in the number of both horizontal pixels and vertical lines to a half in order for screen-size reduction in the digital tuner, is further subjected to double-speed conversion in the television receiver.
The algorithm for double-speed conversion in nature is to optimize a video signal in a standard screen size of 480I without size reduction (720 dots×480 lines). Consequently, in case double-speed conversion is made on a size-reduced video signal, there is a fear to cause image deterioration, e.g. displaying a slant line-a in a step form, as shown in FIG. 1B.
Furthermore, when a character or figure data signal is displayed, e.g. as a 960I signal, line flicker takes place on a character-bas shown in FIG. 1B. Meanwhile, because the format conversion (double-speed conversion function) on a television receiver is designed to optimize video signals, there is a fear that a character or figure image based on a data signal be displayed unnaturally, e.g. with excessive edge-c emphasis as shown in FIG. 1B.